1979 Agway LT 11/36 lawn tractor ?

Where can I get steering parts for my 1979 Agway LT 11/36 lawn tractor ? The fabric disk which connects my steering shaft to the gears has finally torn apart. It's approx 4 1/2" on diameter, and 5/16" thick. It's flexible, and durable: Made of nylon cords, rubber, and ??!!
Has 4 holes in it at 3 1/2 spacing.

Andy.
September 2013